Aryl ether ketones (AEK), notably poly aryl ether ketone polymers (PAEK) have a number of properties which make them useful for applications involving exposure to high temperature or to high mechanical or chemical stress. They are, for instance, useful in the aerospace industry, in offshore drilling and in medical devices.
At the end of the manufacture process of the AEKs, the residual solvents, the unconverted reactants, the reaction by-products along with remaining unrecovered particles of the AEK compounds often form a viscous slurry which is difficult to handle and is prone to plugging the equipment due to the deposition of solids. Furthermore, not only is the slurry classified as hazardous waste, but also the recovery and recycling of the reaction solvents and/or reactants from the slurry is considered to be a difficult procedure which requires high costs.
Conventional means for handling such slurries involves the use of a large quantity of solvent during the manufacture process or the addition of diluent fluids in order to reduce the viscosity or increase the dilution of the slurry. However, this results in larger volumes and costs associated with the handling and disposal of hazardous waste.
Document JP 555-15604 discloses a device for removing volatile substances from a high viscosity composition, and more particularly for removing residual tobacco and remaining solvents from a thermoplastic resin, by using a thin-film evaporator.
Document JP 553-111394 discloses a method for removing remaining monomers from a polyamide resin, by using a thin-film evaporator.
Document US 2011/0201775 discloses a method for removing impurities found in diphenyl sulfone, the solvent used for the synthesis of poly aryl ether ketone polymers and more specifically for the synthesis of poly ether ketone and poly ether ether ketone polymers, in order to improve the polymer properties. One of the approaches employed makes use of a thin-film evaporator.
Document US 2003/0111186 discloses a method for removing all solvent from a solution containing a polyphenylene ether polymer resin, the method employing the use of a wiped thin film evaporator.
There is still a need for a method for recovering residual solvents and reactants from residues related to the synthesis of aryl ether ketones in a simple and cost-effective way, in order to reduce raw material costs, while at the same time minimizing the volume and the hazardous nature of the waste.